1. Field of the Invention
The present invention relates to a solar panel which may be used as a prefabricated module to form a solar collector as an integral part of a roof or wall in the construction of a building.
2. Description of Prior Art
A large number of solar collectors for heating liquids or gases have been developed. Specifically, the literature contains several references which are directly related to this invention. These are as follows:
1. Sparrow, E. M. and Lin, S. H. "Absorption of Thermal Radiation in A V-Groove Cavity". Int. J. Heat Mass Transfer. Vol. 5, pp. 1111-1115. Pergamon Press, 1962.
2. Hollands, K. G. T. "Directional Selectivity, Emittance, and Absorptance Properties of Vee Corrugated Specular Surfaces". Solar Energy 7: 108-116. 1963.
3. Trombe, F., Foex, M. and Vinh, M. Le Phat. "Studies on Selective Surfaces for Air-Conditioning Dwellings". UN Conf. on New Sources of Energy, V. 6, 1961.
4. Close, D. J. "Solar Air Heaters, For Low and Moderate Temperature Applications". Journal of Solar Energy Science and Engineering, Vol. VII, No. 3, pp. 117-124, July, 1963.
Each of the above references broadly teaches that a vee-corrugated surface, whether specular or difuse in nature, will provide an increased absorption of radiant energy. The increase in absorption applies both to direct beam solar radiation and to a lesser extent to difuse radiant energy. The Close publication presents computed data for solar heaters with air flow both under and over different types of absorber plates. The vee-corrugated plate, particularly with a selective coating, was superior in solar collection efficiency to all other forms of absorber plates discussed in Close.
The disclosures of each of the above references fail to recognize that the heat transfer efficiency of a vee-corrugated plate to a fluid to be heated can be further enhanced, if the vee-shaped bends in the absorber plate are closed by a conductive backing plate to form a plurality of contiguous triangular ducts.
For example, Close contemplates the use of a vee-corrugated absorber plate as illustrated in FIG. 2. However, this absorber plate is intended to take the place of the flat absorber plates in one of the arrangements illustrated in FIG. 2, which include absorber plates forming one side of a single large rectangular duct. Accordingly, the structure contemplated by Close would appear to be a large rectangular duct having one side containing a plurality of vee corrugations. Such a structure suffers from the disadvantage that the only heat transfer is from the two surfaces which define each vee on the side of the absorber plate in contact with the fluid being heated.
The above mentioned literature references also fail to provide a thin compact structural module which can be incorporated as an integral part of the roof construction of a building, said module forming the solar absorption and heat transfer functions of a solar collector.
Another prior art reference has used round and triangular shaped ducts as illustrated in U.S. Pat. Nos. 3,903,699 and 3,957,030 to Davis. However, the triangular ducts of Davis are not disposed adjacent to each other to form a flat solar collector plate which can be made an integral part of a sloped roof structure and oriented in an east-west direction for direct absorption of solar radiation. In each of the Davis Patents, an additional energy absorbing reflective surface is required to cause the solar radiation to enter the vee-corrugated surface at a favorable angle. In short, the Davis solar heaters are not designed for use as modular units to be incorporated as an integral part of a building construction and are totally unsuitable for such a use.
An additional prior art reference which appears to be quite pertinent at first blush is U.S. Pat. No. 2,998,006, issued Aug. 29, 1961 to Johnston. Johnston discloses spaced vees on an absorber plate as part of a solar fluid heater. However, the Johnston absorber plate suffers from at least two significant disadvantages. The vees are spaced on the side on which solar radiation is incident which arrangement prevents multiple reflections between the vees and the heat transfer to the fluid is only effected from the back side of the absorber plate. There is no thermally conductive backing attached to the back of the absorber plate of Johnston to enhance the transfer of heat to the fluid and the fluid flows in a large duct which is less effective in transferring heat to the transport fluid than the present invention.
Accordingly, although bits and pieces of some component portions of the novel construction of the present invention are recognized in the diverse type structures of the prior art, a need in the art exists for a highly efficient compact solar panel suitable for use in the modular construction of a solar collector formed as an integral part of the wall or roof of a building, which is not achieved by any of the prior art references discussed hereinbefore.